Today's Dynamic Multipoint Virtual Private Networks (DMVPN) are most commonly deployed over an Internet Protocol/Multiprotocol Label Switching (IP/MPLS) cloud. The IP/MPLS cloud is usually an Internet Protocol version Four (IPv4) based network and the DMVPN sites usually connect to the cloud using IPv4 technology.
Currently, Internet Protocol version Six (IPv6) deployment is spreading around the world. IPv6 is designated as the successor to IPv4, the current standard Internet Protocol used for general internet use. IPv6 offers a number of improvements over IPv4, the most noted of which is the upgrade from the 32-bit address length of IPv4 to a 128-bit length address. This increases the number of total addresses available for networked devices from 232 (approximately 4.3 billion) addresses available with the 32-bit address length of IPv4, to 2128 (approximately 3.4×1038) addresses available with the 128-bit address length of IPv6. This increase in the number of total addresses allows for IPv6 nodes to have as many globally unique addresses as needed, thus eliminating the need for conservation techniques such as network address translation.
With the global deployment of IPv6 spreading rapidly, DMVPN customers will soon have to connect over an IPv6 cloud, instead of the customary IPv4 cloud. This poses a problem for the customers using a DMVPN based on IPv4 technology who cannot afford to upgrade to IPv6 simply because the Service Provider provides IPv6 connectivity.